Roberto Mancini has warned Mario Balotelli that time is running out, and he must work harder if he wants to become one of the world's top players. Mancini left Balotelli out of the squad to face Tottenham earlier this month because of what he felt was a poor attitude in training.

That sparked fresh speculation the 22-year-old could leave City, but Mancini insisted he has no intention of selling his former Inter protégé and has now urged him to focus fully on his football.

Mancini said: "Mario, outside the pitch, is a fantastic guy.

"Sometimes he doesn't understand which is your job, and how his job is important for his life, but I hope for him that he can understand this quickly.

"Now he is 22 but life can go quickly and I hope he can improve everything because as a player he could be like Cristiano and Messi, if he understands that to be like this you should work hard, your mind should be always on your job, not on the other things that are not important. I am very sorry for him for this.

"He has everything to be one of the best players in the world."

Balotelli was spotted in a nightclub in the early hours of the morning prior to the 11 November Spurs game, although no curfew was broken as Mancini had already informed him that he would not be playing.

Mancini has remained fiercely loyal to Balotelli throughout his near two-and-a-half years at City, despite a number of controversial incidents on and off the field.

The 47-year-old hopes he can oversee Balotelli's development into the player he believes that he should be.

Mancini added: "It is not too easy to work with him every day because if you are a manager, you should manage 22 players. This is difficult sometimes but I hope he can change his mind."

A back injury sustained on international duty prevented Balotelli from returning to the side for Saturday's 5-0 win over Aston Villa, and he remains doubtful for Wednesday's home Champions League clash against Real Madrid, but he has trained. Mancini said: "Yesterday he trained with the physio and tomorrow and today he will train with the team and we will see if he can play."